Water resistant cream conditioner

ABSTRACT

A skin protective composition for exhibiting enhanced water repellency and conditioning effects containing aliphatic waxes and hydrophobic silicones in a nonallergenic, non-toxic, cosmetically acceptable carrier. The composition is useful to protect mammals from solar radiation and in the treatment of diaper rash.

The present invention relates generally to a water resistant creamconditioner and more particularly to a novel skin protective compositioncontaining aliphatic waxes and hydrophobic silicones admixed into anonallergenic, nontoxic cosmetically acceptable carrier. Thiscombination exhibits surprisingly enhanced water repellency and skinconditioning effects while substantially eliminating the greasyappearance and tacky feel normally associated with water barrierproducts. Unexpectedly, the composition also enhances moisturization ata level that is far superior to conventional diaper creams.

BACKGROUND OF THE INVENTION

In an attempt to improve product substantivity on skin surfaces, theprior art has traditionally used cationic fatty derivatives, quaternaryammonium salts, resins and gums as additives in cream/lotion bases.Little work has been done to improve the emulsion base itself apart fromroutine product stability adjustments. In recent years, raw materialvendors flooded the market with these additives to further complicatethe dilemma. Indeed the formulation of good cream/lotions has becomesecondary to the incorporation of these inelegant additives to createcompositions which neither look nor feel like cosmetic creams. Instead,they are very sticky, and leave an uncomfortable feel throughout theusage period. User compliance with such compositions is therefore quitepoor. Moreover, the use of certain cationic/quaternary ingredients willcause skin and eye irritations. In addition resins and gums can cause"powdering" upon drying from too great a friability which furthercontributes to poor product appearance and inferior skin substantivity.

As a result, many products on the market today give the consumer a falsesense of security because of the inability of the active ingredientsthereof to remain in place when the user is engaged in water activities,or encounters rain or other liquids which literally wash the activeingredients away.

The present invention comprises an effort to address this problem andprovide elegant topically applied preparation which is water repellent,moisturizes the skin, and further serves as a novel drug delivery systemin which sunscreens, and like topically effecting drugs/chemicals can beapplied to human skin. The base composition of the present invention canbe formulated to provide a variety of cosmetic, presonal care and/orpharmaceutical preparations, such as hand creams, lip balm, facialcosmetics, diaper creams, ostomy creams, medicinal creams and the like.Thus, a preparation is herein described which possesses many positiveattributes including superior water repellency, resistance to beingwashed off, physiological mildness, and a pleasant feel which enhancesuser comfort and hence, user compliance.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to a pharmaceutical/cosmetic preparationform in a base containing a synthetic aliphatic wax, that is, a highmolecular weight C₁₈ -C₃₆ saturated synthetic fatty acid wax admixedwith one or more hydrophobic silicones. The preparation when topicallyapplied to human skin exhibits surprising enhanced water repellency andskin conditioning effects while substantially eliminating the greasyappearance and tacky feel normally associated with water barrierproducts. The preparation is uniquely adapted for use as a diaper creamin that it combines moisturization with water resistance therebysubstantially reducing incidents of diaper rash.

Accordingly, it is a prime object of the present invention to provide anew and improved water resistance cream conditioner.

Another object of the present invention is to provide a unique skinprotective composition providing enhanced water repellancy and skinconditioning properties without a greasy appearance or a tacky feel.

A further object of the present invention is to provide a novel andunique cream conditioner especially useful in mitigating the effect ofdiaper rash on newborns and infants.

Still another object of the present invention is to provide a new andimproved water resistant composition into which conventional sunblockers can be readily incorporated to provide a non-greasy, non-tackysunscreen material.

These and still further objects as shall hereinafter appear arefulfilled by the present invention in a remarkably unexpected fashion aswill be readily discerned from a careful consideration of the followingdetailed description of exemplary embodiments thereof.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention relates to a pharmaceutical/cosmetic preparationand more particularly to a cream/lotion base containing a syntheticaliphatic wax, that is, a high molecular weight C₁₈ -C₃₆ saturatedsynthetic fatty acid wax such a Syncrowax® or an equivalent thereofdeveloped for such use, admixed with one or more hydrophobic silicones,such as, cyclomethicone, dimethiconol, dimethicone, phenyltrimethicone,and the like.

The foregoing mixture forms a film when it is topically applied to asurface. The film thus formed is resistant to wetting by moisture.Further, as will appear, the base composition of the present inventionfar superior water barrier properties than can be obtained with thequaternaries; cationic polymer resins and gums heretofore employed aswaterproofing agents. Further, no flaking or leaching of the productoccurs even during extended use. An important factor of this newcombination of ingredients is that it provides a silky and non-greasylubricant which enables the active ingredient disposed therein to bespread evenly and smoothly upon the skin.

The amount of C₁₈ -C₃₆ aliphatic saturated fatty acid wax andhydrophobic silicones used in this composition can, as will appear, varygreatly depending on the degree of waterproofing and skin feel desiredfor a particular product.

Preferably, the C₁₈ -C₃₆ saturated synthetic fatty acid wax will rangefrom about one to about ten percent by weight of the total compositionand the hydrophobic silicones will vary from about two to about twentypercent by weight.

A number of film-forming agents, polymers, and cosmetic resins can beemployed in combination with the present base formulation when productdesign considerations warrant their inclusion. Such agents, polymers andresins include: polyvinylpyrrolidone; PVP/eicosene copolymer;vinylpyrrolidone/vinyl acetate copolymers in which the monomer ratioranges from 70/30 to 30/70; vinyl acetate/unsaturated carboxylic acidcopolymers, for example 90% of vinyl acetate and 10% of crotonic acid;terpolymers of methyl methacrylate/stearyl methacrylate/stearylmethacrylate/dimethyl-aminoethyl methacrylate which have been completelyquaternised with dimethyl sulphate, the monomers being used particularlyin the ratio 20/23/57; a terpolymer of vinyl acetate/allylstearate/allyloxyacetic acid, especially in the ratio of 80/15/5; maleicanhydride/methyl vinyl ether copolymers such as "Gantrez AN" and theethyl, isopropyl and butyl esters thereof; and maleic anhydride/butylvinyl ether copolymers. Another unexpected advantage of the presentinvention occurs when those polymers which are known to produce a stickyor tacky feel in conventional cream bases are used in the presentinvention, they create a smooth and silky composition which is neithertacky nor sticky.

For pharmaceutical preparations, a number of medications may be employedas an active ingredient when uniformly dispersed throughout thecream-conditioner of the present invention including steroids, such as,hydrocortisone, betamethasone and the like; antibiotics, such asbactimycin, erythromycin, and the like; antifungals such as, tolnaftate,clotrimazole, and the like; and other popular topical reagents such asbenzoyl peroxide for the treatment of acne; diethyltoluamide for insectrepellency and the like.

A prototype water barrier cream embodying the present invention toprovide water repellency and conditioning can be formulated as follows:

    ______________________________________                                        Ingredient        % (w/w)                                                     ______________________________________                                        Mineral Oil       67-87                                                       Syncrowax ® HRS-C                                                                           1-2                                                         Syncrowax ® HGL-C                                                                           1-4                                                         Hydrophobic silicones                                                                            5-20                                                       (Q.sub.2 1401)                                                                Silica            6                                                           dl-alpha tocopherol                                                                             .1-1                                                        ______________________________________                                    

To prepare the cream conditioner base of the present invention forsunscreen application, several ultraviolet absorbing sunscreen agentscan be incorporated therein with good product stability. The agentsinclude oxybenzone (2-hydroxy-4-methoxy-benzo-phenone); dioxybenzone(2,2'-dihydroxy-4-methoxy-benzophenone); amino benzoic acid; cinoxate(2-ethoxyethyl-p-methoxycinnamate); diethanol-amine-p-methoxycinnamate;digalloyl trioleate ethyl 4-bis (hydroxypropyl) aminobenzoate;2-ethylhexyl-2-cyano-3,3-diphenylacrylate;ethylhexyl-p-methoxycinnamate; 2-ethylhexyl salicylate; glycerylaminobenzoate; homosalate (3,3,5-trimethylcyclohexyl salicylate);triethanolamine salicylate; 2-phenylbenzimidazole-5-sulfonic acid;sulisobenzone (2-hydroxy-4-methoxybenzophenone-5-sulfonic acid);Padimate A (amyl-p-dimethylaminobenzoate); Padimate O (octyl dimethylpara aminobenzoate); 4-t-butyl-4'-methoxy-dibenzoylmethane; thecombination of 2-hydroxy-1, 4-naphthoquinone with dihydroxyacetone; andmenthyl anthranilate.

In one practice of the present invention, a suitably sized stainlesssteel tank is charged with mineral oil and the dual mixers (the sweeprotating at about 10 RPM clockwise while the turbine rotates at about 12RPM counterclockwise) are activated.

Next, the batch is heated to 110° C. and, while heating, Syncrowax® isadded (sweep at 14 RPM and turbine at 24 RPM) until it is completely andhomogeneously dispersed. When desired for formulation purposes, otherwaxes or fatty alcohols will be added at this time while turbinerotation is maintained.

Next, the silica or other thickener such as stearalkonium hectorite,propylene carbonate and the like is added to the batch while the mixersare maintained at the higher speed and the temperature is maintainedabove 78°-80° C. for one hour. Thereafter, with continued stirring, asuitable antioxidant, such as dl-alpha-tocopherol, is added to the batchand blended therethrough.

The batch is then cooled at a rate of about 0.5° C./minute. When atemperature of 40°-50° C. is reached, the hydrophobic silicone (DowQ21401) is added with continuous mixing until the batch reaches roomtemperature, i.e., from about 10° to about 25° C. The batch, subject toQuality Control approval, is now ready for packaging.

To further aid in the understanding of the present invention and not byway of limitation, the following examples are presented.

EXAMPLE I

A suitably sized stainless steel tank is charged with mineral oil andthe dual mixers (the sweep rotating at about 10 RPM clockwise while theturbine rotates at about 12 RPM counterclockwise) are activated.

Next, the batch is heated to 110° C. and, while heating, Syncrowax® isadded (sweep at 14 RPM and turbine at 24 RPM) until it is completely andhomogeneously dispersed. When desired for formulation purposes, otherwaxes or fatty alcohols will be added at this time while turbinerotation is maintained.

Next, the silica or other thickener such as stearalkonium hectorite,propylene carbonate and the like is added to the batch while the mixersare maintained at the higher speed and the temperature is maintainedabove 78°-80° C. for one hour. Thereafter, with continued stirring, asuitable antioxidant, such as dl-alpha-tocopherol, is added to the batchand blended therethrough.

The batch is then cooled at a rate of about 0.5° C./minute. When atemperature of 40°-50° C. is reached, the hydrophobic silicone (DowQ21401) is added with continuous mixing until the batch reaches roomtemperature, i.e., from about 10° to about 25° C. The batch, subject toQuality Control approval, is now ready for packaging.

EXAMPLE II

Using the foregoing procedure of Example I, a lip moisture stickembodying the present invention was prepared having the followingcomposition (in weight percent). The ingredients, other than thesynthetic aliphatic wax and hydrophobic silicones which are key, areshown as representative and know equivalents may be substituted for anyof the listed non-key ingredients throughout these Examples.

    ______________________________________                                        Lip Moisture Stick                                                                              % (w/w)                                                     ______________________________________                                        Syncrowax ® HGL-C                                                                           12                                                          Hydrophobic silicones                                                                           15                                                          Stearyl alcohol   20                                                          Castor oil        25                                                          Cetyl Alcohol      3                                                          Mineral Oil       25                                                          ______________________________________                                    

EXAMPLE III

Using the procedure of Example I, a water proof sunscreen cream wasprepared having the following composition (in weight percent):

    ______________________________________                                        Mineral Oil         39.5-78                                                   Octyl methoxycinnamate                                                                             1-7.5                                                    Syncrowax ® HRS-C                                                                             5-10                                                      Benzophenone-3      1-5                                                       Silica              2-10                                                      Hydrophobic silicone                                                                              5-15                                                      Stearalkonium hectorite and                                                                       1-6                                                       propylene carbonate                                                           ______________________________________                                    

EXAMPLE IV

Using the procedure of Example I, a medicated cream was prepared havingthe following composition (in weight percent):

    ______________________________________                                        Medicated cream      %                                                        ______________________________________                                        Hydrocortisone       0.5                                                      Mineral Oil          62.5                                                     Syncrowax ® HRS-C                                                                              2                                                        Syncrowax ® HGL-C                                                                              4                                                        Silica               6                                                        Hydrophobic silicone Q21401                                                                        15                                                       Hydrophobic starch   10                                                       ______________________________________                                    

EXAMPLE V

Using the procedure of Example I, a water barrier cream was preparedhaving the following composition (in weight percent):

    ______________________________________                                        Water Barrier Emulsion                                                        ______________________________________                                        Water                80.50                                                    Syncrowax ® HGL-C                                                                              3.5                                                      Glyceryl stearate and                                                                              2                                                        PEG 100 stearate                                                              Sorbitan stearate    2                                                        Polysorbate 60       2                                                        Hydrophobic silicone Q21401                                                                        10                                                       ______________________________________                                    

EXAMPLE VI

Using the procedure of Example I, a prototype diaper cream formula wasprepared and thereafter clinically tested at the Pediatric Clinic ofParis Hospital in France. The test formula (in weight percent) consistedof:

    ______________________________________                                        Mineral oil         59.66                                                     Aliphatic waxes     5.34                                                      Hydrophobic silicone                                                                              14.00                                                     PVP/eicosene copolymer                                                                            2.00                                                      Dry-flo starch      13.00                                                     ______________________________________                                    

All cases tested showed surprising improvement or suppression ofsymptoms related to dryness, itching and redness of the buttocks of thebabies. This was only after five days of application.

    ______________________________________                                                    Number of patients                                                Formula #   tested        Improvement                                         ______________________________________                                        276-2       6             >75%                                                            2             >95%                                                            2             >50%                                                75-5        6             >75%                                                            1             >95%                                                            2             >50%                                                77-1        5             >75%                                                            2             >95%                                                            1             >50%                                                79-1        6             >75%                                                            2             >95%                                                            1             >50%                                                ______________________________________                                    

EXAMPLE VII

A sun screen cream was prepared according to Example III and testedaccording to the procedures and the criteria outlined in the "ProposedMonograph for OTC Sunscreen Drug Products" issued by the F.D.A. on Aug.25, 1978 (43 Fed. Reg. 166 at 38206-38269).

The purpose of the tests was to determined the Sun Protection Factor(SPF) efficacy on the skin of human subjects, before and after a totalof 80 minutes of water immersion.

The wet control test material, Johnson & Johnson SUNDOWN™ moderate(SPF=4), and the static control, 8% Homosalate, were prepared accordingto FDA specifications (Fed. Reg., Ibid at 38259). The test product wasprepared according to Example III.

The light source was a Solar Ultraviolet Simulator, Model 10S (Fed.Reg., Ibid at 38260) consisting of a 150 watt Xenon arc lamp with allrequired optical elements and a regulated power supply.

A total of five fair skinned subjects (all female, age range 28 to 60)with skin types I, II, and III were placed on test.

Testing was preformed using the following procedures.

Test Site Inspection

The physical examination determined the presence of sunburn, suntan,scars, active dermal lesions, and uneven skin tones on the areas of theback to be tested. The presence of nevi, blemishes or moles wasacceptable if they would not interfere with the study results. Excesshair on the back, if present, was shaved.

Test Site Area

A test site area served as an area for determining the subject's MinimalErythema Dose (MED) after application of either the sunscreen product orfor determining the subject's MED of unprotected skin (control site).The subject's MED is the time of exposure that produces the minimallyperceptible erythema at 16 to 24 hr post-exposure. The area to be testedwas the back between the beltline and the scapulae (shoulder blade) andlateral to midline. The test site areas were horizontal or vertical, andrectangular or square. Each test site area for applying a product orstandard control was 50 cm sq. These test sites were outlined withgentian violet while the person to be tested was in an upright position.

Test Subsite Area

Each test site area of the test was divided into seven subsite testareas that were at least 1 cm sq. For both the test product and thecontrol product, two test site areas were used--one for before waterimmersion and one for after 80 minute water immersion. Placement of testsite areas were randomized among the subjects. One additional test sitearea was used for 8% HMS SPF determination on each subject as per FDAProposed Monograph.

Application of the Test Material

To insure standardized reporting and to define a product's SunProtection Factor (SPF) value, the application of the product isexpressed on a weight basis per unit area which establishes a standardfilm. The test sunscreen product and the sunscreen standard applicationis 2 mg/cm sq or 2 ul/cm sq. The 50 cm sq test site area requires 100 mgof a product or 100 ul (assuming a specific gravity of 1) to obtain astandard 2 mg/cm sq test application. For the test product, a cream, theviscosity is such that the material was weighed and applied to theappropriate areas by spreading with a finger cot.

Waiting Period

Before exposing the test site areas after applying a product, a waitingperiod of at least 15 minutes was employed.

Test Site Irradiation

A series of UV light exposure (units of time) were administered to thesubsites on each subject with the solar simulator. One series ofexposures was administered to the untreated, unprotected skin todetermine the MED. The MED is the time of exposure that produces theminimally perceptible erythema at 16 to 24 hour post-exposure. The MEDof the subject's unprotected skin was determined prior to the test day,then again on test day.

Each of the protected test sites (controls and/or test sunscreenproduct) were also exposed to UV light. The standard time intervalsselected are a geometric series represented by (1.25)n, wherein eachexposure time interval is 25 percent greater than the previous time.(The reason for using the geometric sequence of UV exposure is tomaintain the same relative uncertainty, expressed as a constantpercentage), independent of the subject's sensitivity to UV light,regardless of whether the subject has a high or low MED). The exactseries of exposures to be given was determined by the MED of theunprotected skin.

After UV irradiation of one test site each for both the test sunscreenand the above-cited control sunscreens, each subject entered thewhirlpool for 20 minute; whirlpool agitation was at a moderate level.This was followed by a 20 minute rest period, followed by a second 20minute period of activity in the whirlpool, followed by a second 20minute rest period, followed by a third 20 minute period of activity inthe whirlpool, followed by a third 20 minute rest period, followed by afourth 20 minute period of activity in the whirlpool. Care was taken andeach subject was continuously monitored to insure that the "after" testsite areas were untouched. At the conclusion of the 80 minute watertests, the test sites were air dried without toweling. The secondprotected test site of both the test sunscreen and the above citedcontrol was then exposed to UV light, using the identical method andseries of exposures as were used for the "before" UV light irradiation.

Each subject reported back at 16 to 24 hours postexposure, at which timeeach test site area was read to determine the Minimal Erythema Dose(MED) of both the unprotected and the protected skin.

For both the test sites irradiated prior to water immersion and the testsites irradiated after 80 minutes water immersion, the SPF of the testsunscreen is then calculated from the exposure time interval required toproduce the MED of the protected skin, and from the exposure timeinterval required to produce the MED of the unprotected skin (controlsite), i.e., ##EQU1##

Results and Conclusions

No adverse reactions were observed in any of the subjects who weretested as per the testing procedures described above. The Sun ProtectionFactor (SPF) value for the sunscreen, as well as for the controls, areas follows:

    ______________________________________                                                                 SPF Labeling                                         Product         SPF      Category                                             ______________________________________                                        95-90-03                                                                      Before Immersion                                                                              16.70    15.00 or greater (Ultra)                             After Immersion 16.70    15.00 or greater (Ultra)                             Controls                                                                      J&J SUNDOWN Moderate                                                          Before Immersion                                                                              5.00     4.00 to 5.99 (Moderate)                              After Immersion 4.60     4.00 to 5.99 (Moderate)                              8% Homosalate   4.40     4.00 to 5.99 (Moderate)                              ______________________________________                                    

From the foregoing, it is apparent that new and useful water resistantcomposition has been herein described and illustrated which fulfills allof the aforestated objectives in a remarkably unexpected fashion. It isof course understood that such modifications, alterations andadaptations as may readily occur to the artisan confronted with thisdisclosure are intended within the spirit of this disclosure which islimited only by the scope of the claims appended here.

Accordingly, what is claimed is:
 1. An anhydrous topical composition ofmatter for water proofing mammalian skin containing a pharmacologicallyacceptable carrier selected from the group consisting of mineral oil,vegetable oil, and an aliphatic/branched chain ester and, in weightpercent, from about 1 to about 10 percent C₁₈ -C₃₆ saturated syntheticfatty acid wax and from about 2 to about 20 percent anhydroushydrophobic silicone, said wax and said silicone being dispersed in saidcarrier.
 2. A composition according to claim 1 in which said hydrophobicsilicone is selected from the group consisting of: cyclomethicone;dimethicone; phenyltrimethicone; dimethiconol; and mixtures thereof. 3.An anhydrous topical composition containing in weight percent from about67 up to about 87 percent mineral oil, from about 2 up to about 6percent (C₁₈ -C₃₆) saturated synthetic fatty acid wax, from about 5percent up to about 20 percent hydrophobic silicone; about 6 percentsilica; and from about 0.1 up to about 1 percent dl-alpha tocopherol. 4.A composition of matter according to claim 3 in which said hydrophobicsilicone is selected from the group consisting of: cyclomethicone;dimethicone; phenyltrimethicone; dimethiconol; and mixtures thereof.